Investigating the photodegradation-induced visual degradation and its underlying mechanisms of warehousing bamboo

Abstract

Bamboo is a sustainable and environment-friendly polymer. In order to investigate the effect of photoaging on the service-life of bamboo, ultraviolet aging (UV-aging), light-avoidance −90 %RH (AL-90 %RH), light-avoidance (AL) and control were continuously monitored for 26 weeks under four kinds of light conditions. The surface color, micro-morphology and surface interfacial composition of comparing various bamboo samples during storage. The results showed that the total color difference for the cortex (9.758 ± 0.712) and pith (1.325 ± 0.075) under AL conditions were lower than the other three sets of storage conditions, and L* values were reduced by 56.42 % and 53.73 %, respectively. In addition, microflora and grooves were formed on the surface of bamboo stored under AL-90 %RH conditions. Meanwhile, catheters were the main channels for the propagation of mycelium in bamboo. Moreover, the Cox/unox value (an oxygenated to unoxygenated carbon ratio of 0.964) increased sharply under these conditions. UV-aging destroyed the texture and structure of bamboo tissue cells and surfaces, degraded the surface lignin content by 18.89 %, and exposed more observable hemicellulose and cellulose functional groups, thus increasing the carbon binding energy and becoming more difficult to degrade. Finally, the Long Short-Term Memory (LSTM) neural network model was used to predict the fading of the surface color and the volatile compounds after aging, and different photoaging color indication systems were established. Exploring the aging mechanism of bamboo during storage is important for promoting the development of bamboo industry and replacing plastic products, and helping in determine the practical applications of the proposed strategies, their economic benefits and limiting of bamboo photodegradation under optimal warehousing conditions. This meet the current requirements of sustainable development by preserving bamboo resources and use instead renewable resources for both environmental and economic benefit.